Acanthosis nigricans (AN) is characterized by velvety hyperpigmented thickening of the skin, most often over posterior neck, axillae, & groin. This cutaneous finding is common in obese children, & usually associated with insulin resistance & hyperinsulinemia. It has been hypothesized that increased binding of insulin to insulin-like growth factor I (IGF-1) receptors on keratinocytes may lead to AN, augmented by action of epidermal growth factor (EGF). We will investigate expression of receptors for IGF-1 and EGF in AN lesions & normal skin from patients with AN.